Musnad Ahmad 30:2804

I read to Abd al-Rahman: Malik, and Ishaq narrated to us, he said: Malik narrated to us, from al-Ala’ ibn Abd al-Rahman ibn Ya’qub, that he heard Abu al-Sa’ib, the freed slave of Hisham ibn Zuhrah, saying: I heard Abu Hurayrah saying: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever performs a prayer in which he does not recite the Mother of the Quran (Al-Fatiha), it is deficient, it is deficient, it is deficient, not complete." I said: "O Abu Hurayrah, sometimes I am behind the Imam." He squeezed my arm and said: "Recite it to yourself, O Persian, for I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: 'Allah the Almighty said: I have divided the prayer between Myself and My servant into two halves; half is for Me and half is for My servant, and My servant shall have what he asks for.'" The Messenger of Allah (peace and blessings of Allah be upon him) said: "Recite. The servant says: {All praise is due to Allah, Lord of the worlds}, Allah the Almighty says: 'My servant has praised Me.' The servant says: {The Entirely Merciful, the Especially Merciful}, Allah the Almighty says: 'My servant has extolled Me.' The servant says: {Sovereign of the Day of Recompense}, Allah the Almighty says: 'My servant has glorified Me.' The servant says: {It is You we worship and You we ask for help}, Allah the Almighty says: 'This verse is between Me and My servant, and My servant shall have what he asks for.' The servant says: {Guide us to the straight path - the path of those upon whom You have bestowed favor, not of those who have evoked [Your] anger or of those who are astray}, these are for My servant, and My servant shall have what he asks for."